diff --git a/cubesatsim/cubesatsim.ino b/cubesatsim/cubesatsim.ino
index 5b0a5644..33ba32d2 100644
--- a/cubesatsim/cubesatsim.ino
+++ b/cubesatsim/cubesatsim.ino
@@ -3556,7 +3556,7 @@ void config_gpio() {
 //  pinMode(SQUELCH, INPUT);	// Squelch from TXC
 
 //  if (digitalRead(BPF_PIN) == FALSE) {  
-  if (digitalRead(BPF_PIN) == FALSE) {  // force BPF present
+  if (digitalRead(BPF_PIN) != FALSE) {  // force BPF present
     Serial.println("BPF present - transmit enabled");
     filter_present = true;  
   }